They insist that Independents should abide by the same rules as political parties, which cannot give charitable donations from state funding.

Twelve non-party senators have been put under pressure to explain how they spend the €23,383 that they get every year.

Independent TDs get €46,000. This is on top of a basic wage of €92,000 for TDs and €65,000 for senators.

The payments are unvouched and untaxed -- meaning that they can spend it as they please.

By contrast, political parties can only spend their leaders' allowances on research, policy formulation and other parliamentary activities.

Independent senator Fiach Mac Conghail, the director of the Abbey Theatre, said his €23,000 went "to support arts projects and charities", as did his his basic €65,000 salary. He added: "Receipts kept. No personal gain."

Jillian van Turnhout, another senator who was appointed by Taoiseach Enda Kenny, said she used the money for charity.

She added: "As a senator, you're asked quite a lot to give charitable donations. I would have done that anyway, so I'm trying to see how I can put the money to good use."

However, Labour's Emmet Stagg, the Government's deputy whip, said the €46,000 for Independent TDs and €23,000 for senators should not be given to good causes and that Independents should have to play by the same rules as others.

Mr Stagg added that he could not understand "why Independents need a leader's allowance".

Public Spending Minister Brendan Howlin is currently reviewing the payments and is widely expected to force the Independents to account for how the money is spent.